Telephone system



P 7, 1931- R. STOKELY I 1,799,653

TELEPHONE SYSTEM I Filed April 5, 1929 5 Sheets-Sheet 1 wvavmn H. L. Era/ray WW7 April 7, 1931.

R. L. STOKE LY TELER HONE SYSTEM- //v VENTU/i R L. Bro/ray II QIII AII I A T THEM/E) Patented Apr. 7, 1931 umrn STATES RAY L. STOKELY, or FLORAL PARK, new YORK, ASSIGNQR T BELL TELEPHONE, LABORATORIES, INCORPORATED, on NEW YORK, N. r., ..a CORPORATION or NEW,

YORK

PATENT OFFICE 1 'rnnnrnonn SYSTEM This invention relates to telephone systems and particularly to systems operated on the pre-payment basis.

- that, when taken in use for extending a calling line'to an operators position, the coin collecting means is disabled and the trunk convertedfrom a repeater typetrunk to a direct'connection type trunk free from any electrical obstructions.

This invention has been illustrated in the accompanying drawings, in which Fig. 1 shows a calling subscribers line provided with coin box equipment and a portion of a trunk, arranged in accordance with the principles of this invention, to which the sub: scribers line has access through a line finder. 5

Fig. 2 shows the remaining'port-ion of this trunk. Fig. 3 shows a selector associated with the trunk and a connector in diagrammatic form having access to a called local subscribers line, and another trunk accessible by said selector. This second trunk is also arranged in accordance with the principles of this invention and terminates at an operators position where the plug of an operators cord has been shown in diagrammatic form.

Referring now to the drawings generally, the trunk'CT terminates in Fig. 1 at a line finder .4, through which calling subscribers may be connected to the trunk. TrunkCT also terminatesjinjacks 5 and- 6 at an operators position A, so that the operator, at this position maycontrol coin collectionthrough a cord, indicated in diagrammatic form.

Trunk CT, besides embodying the features of this invention, also has means for control= ling collection of coins at predetermined periods of conversation according to the invention of Messrs. O. A. Friend and WLJ,

Heitsmith covered in a 'copending applic'aformed when the connect-ion between two subscribers is released. It is also providedwith means whereby the coin may be refunded automatically when the operator at AB removes her plug 301 from jack 302 in cases where connections are extended over the trunk AT and where no charges are made for the calls. It should be understood that the line finder 4:, selector 304 and connector 305 may be of any well-known type com monly used in the telephone art and have nection'is extended from the calling sub scriber at 1 to the local subscriber at 800 and when a connection is extended from the subscriber at 1 through trunk AT to a distant subscriber through the operators position at AB.

Nhen the calling subscriber-"at 1 takes 111s receiver off the hook and deposits a coin in the coin equipment to enable him to make the call, the line finder 4L is actuatedto connect his line with trunk CT. As the circuits" for extending the connection to the trunk forms no part of this invention, no descrip t1on w1ll be made thereof. It will be assumed, therefore, thaton the-establishing of this connection a circuit will be completed through the calling subscribers loop for the operation of relay 200 in trunk CT. This circuit'may be traced asfollows: battery, upper inner armature and back contact of relay 201, upper'make-beforabreak contacts of relay 202, lower make-before-break con-j tacts of relay 203', lower inner armature anw back contact of'relay 8, lower armature'and back contacts of relay 9, lower outer armaw front contact of-relay206 to ground.

ture and back contact of relay 10, lower inner armature and back contact of relay 11, the tip and ring conductors of the trunk through the line finder 4 and the loop closed through the subscribers set at 1, the upper armature and back contact of relay 11, upper outer armature and back contact of relay 10, upper armature and back contacts of relay 9, upper inner armature and back contact ofrelay 8, retardation coil 204, wind ng of relay 200,lower outer armature and back contact of relay 203 to ground. Relay 200 in operating closes a circuit for the operation of relays 12 and 206. The circuit for relay 12 may be traced from battery, through the upper inner armature and back contact of relay 207, Winding of relay 12, upper armature and back contact of relay 208, upper inner armature and back contact of relay 203 to ground at the armature and front contact offrelay 200. The circuit for the operation ofrelay 206 may be traced from the same bat tery. as the circuit for relay 12, through the winding of relay 206 to ground at relay 200. Relay 12 in operating, closes a connection to ground 'at its lower inner armature and front contact through retardation coil 13 to the sleeve conductor for line finder 4, to hold it busy and to maintain the connection in a manner well-known in the art. Thepurpose of retardation coil 13 is to permit supervisory tones to be connected to the sleeve circuit. Relay 12 also connects the tip and ring leads 14 and 15 from one side of condensers 16 and 17 towards the selector 304. The resistances 210 and 211 will be connected in the tip and ring conductors from the see lector 304 at a certain period during the establi'shing of this connection as will become apparent as the'des'cription proceeds, and will then serveto prevent high voltage hattery from the selector 304 from surging throughthe condensers 16 and 17 intothe relay 212 and cause it to operate falsely when relay203 is operated as hereinafter described.

Relay 206 in operating closes a circuit for the operation of relay 203 as follows: battery, winding of relay 203, armature and This relayin operating provides a holding circuit for relay 12 independent of the ground at relay 200 by the closing of its upper makebefore-break contacts to ground. Relay 203 in operating also removes the shortcircuit from the resistance 213 to ground for relay 200 sothat relay 212 will not operate even though relay 203 in operating opens the bypass circuit for relay 212 through its lower makebefore-break contact. 1t should be noted that the circuit hereinbefore traced for relay 200 now extendsthroughthe lower inner armature and front contact of relay 203, winding'of relay 212 tobattery atrelay201 and to ground through resistance 213. Relay 212 is marginal in its operation and willv tion of relay 216. through its armature and front contact over a circuit through the lower outer armature therefore not operate in this circuit. The operation of relay 203 also closes a bridge across the tip and ring conductors towards the selector 304. This brid e includes relay 219 and retardation coil 220 due to the operation of relay 12. The purpose of the bridge is to cause the operation of the usual pulsing relay (not shown) in the selector circuit, so that the selector will be ready for the reception ofdialing impulses. Means in the selector (not shown) now cause the transmission of a dial tone over the tip conductor towards the calling subscriber through the resistance 211, conductor 14, and condenser 16 to the calling subscriber to indicate that the circuit arrangement is now ready for transmission of dial pulses and for the deposit of a coin in payment for the first" conversation period.

As hereinbefore described the subscriber deposits a coin in the coin equipment when originating the call. The operating magnet of thisequipment has been marked 18 and a coin has been indicated at 19. The deposit of the coil closes a circuit to ground in the coin equipment'for the operation of relay 212. It should be noted that this ground is connected through the coin magnet 18 and the subscribers set at 1 with the ring conductor of the trunk CT over the circuit hereinbefore traced for relays 200 and 212. Relay 212 will now operate as this ground shunts the re sistance 213 and the winding of relay 200.

front contact of relay 212, winding'of relay 201 to ground (not shown) on the sleeve of the selector 304. This ground connection is established on the operation of the pulsing relay in the selector. Relay'201, in operating, closes a locking circuit for itself froin battery, through, its upper make-before-break contacts, to the ground on the sleeve of selector 304. Relay 212 is now released due to the removal of battery from the circuit by the operation of relay 201. Relay 201 in operating closes anobvious circuit for the opera- Relay 216 is locked and back contact of relay 8. Relay 216 in operating closes .an obvious circuit for the operation of relay 202. The purpose of the operation of this latter relay will become apof no importance in connection with this invention. Relay 201 also prepares the-dialrelay-217 through its lower inner'armature a'ndfront contact to the ring conductor of the calling line. i 'i i Relay 217now operates from the ground at thecoin'equipment andcloses an obvious. circuit for .the operation ofrelay- 208.' Relay.

from the ring conductor, ithroughthe upper armature and front contact of relay 217, winding of relay 219, retardation coil 220 to the tip conductor. 2 1

It shouldbe noted that onthe release of relay 200, relays 206 and 203 were released in succession so that the originalbridge established'by relay 203 is broken but relay 203 is slow in releasing so that this bridge is not open until the above mentioned substitute bridge is established. Relay 203 in releasing short circuits the resistances 210 and 213. It also disconnects relay 212'from the line by establishing theabove mentioned by-pass circuit for this relay. It should be remembered that relay 212 had already been released on the operation of relay 201. The circuits are now ready for the reception of dialing impulses. I

The subscriber now dials the number of the desired local subscriber and relay 217 responds to these pulses to open and close the bridge for the pulsing relays in the selector 304 and connector 305. It .should be mentioned here that on the first release-of relay 217relays 208 and 12 are released and due to the fact that relay 208 is slow to operate it will not operate again during pulsing. The relay 219 and resistance 220 are excluded from the bridge during pulsing due tothe release of relay -12. Relay 217 will be per r manently released when relay'9 is operated as hereinafter described and hence relay 208 will not remain operated after this. re'lease'of relay 217. Relay 12 is kept released during pulsing to prevent the'pulsing from affecting the circuit through the calling subscribers' line through the condensers 16 and 17 It should be noted however that relays 208 and ,12 are reoperated after pulsing to maintain the connection. between the calling SLlbSCIlb ers line and the selector telephonically.

This is of importance in connection'wit tensions to an operatorsposition at AB as will become apparent asthe description pro ceeds. The pulses of the; first digit Ioperate the selector 304 to .select a connector. 305 which in turn is operated by the pulses of the second and third digits-to select'the desiredsubscriber at 300. The connector 305 infind-.

selector bank 25.

ing the line of thedesired subscriber is'op-j eratedto transmit signaling current over this line to call the subscriber; As stated the selec'tor .304 and connector. 305 may be ofany well-knowndesign and their operation 1s not described in detail as they form no part of this invention. It is su'fiicient to say that,

whenthe called subscriber at .300 answers, current over the tip and ring conductors of the trunk CT is reversed This reversal of current causes the operation of the polarized. relay-222. l

Relay 222 in operating closes a circuit for."

theoperation of relay 223 as follows :battery, winding of relay .223 and its -make-beforetureand front contact to the ground at relay 202 independent of the connection through relay 222. Relay 224 is also operated-by; the operationlof relay 222 i from battery through the winding of relay 224,- upper ar-. mature and back contact of relay 225. to the ground at relay 202; Relay224 in operating the ground at relay 202 and also closesan ob= vious circuit to the same ground for the operation of relay 225. These two relays are now held under control of relay 202 independent of relay 222.: Relay 224 in operating reversesv the tip andv ring conductors to the called subscriber to release relay 222 and for other purposes of no'importance in conneccloses a locking circuit fOIfltSGlf.llllIOllglIlllSf I inner upper armature and front contactsto.v

sleeve of selector 304. Relay 20 in operating provides a locking circuit for itself through its upper inner armature and front contact, to

' ground at selector 304independent of relay 223. Relay 20 also closes a'conneetion to,

ground for the start lead to the interrupter equipment 23 to start it to function to transmit ground impulses through lead 24 of the This bank andtwo others 26 and 27 form parts of an ordinary step-by The relay 9 is".

scriber to the called subscriber over its arma-j.

tures and frontcontacts andztalking conducnection over trunk CT-is free from all elec trical incumbrances and is maintained in Y this condition until theconnection-is re I leased The operation of relay 9 removes the pulsing relay 217 from controlover the call Relating now to the operation of rela 20,

acircuit is completed by the operation 0 this relay for the stepping magnet 28 to advance the brushes of the banks 25, 26 and 27 at the rate at which the pulsesare received over lead 24. The interrupteriequipment 23 may be so arranged that a connection to ground is established over lead 24 for a'short interval every eighteenth second. The stepping magnet will therefore be operated to advance the brushes one ste every eighteenth second, by a circuit from attery, through the winding of .stepping magnet 28, lower armature and front contact of relay 225, lower inner armature andfront contact of relay 20, brush of bank .25, the zero terminal of this bank, through lead'24, :to ground at the interrupter equipment 23. hen the brush of bank 25 comes to rest on the first terminal the second impulse .is'transmittedover lead 24 which isxconnected to the first eighteen terminals including'the zero or normal terminal. The stepping magnet will therefore 'be operated eighteen times and the brushes of the switch advancedto terminal number 18. Inthis position the stepping magnet 28 passes out of control of the interrupter equipment-23 anda circuit is established over the brush of bank 25, from battery, through :the stepping imagnet 28 andthe-circuit hereinbetore traced, to the'eighteenth terminal andthevbrush of'bank 25, upper inner armature and backcontactot relay 10, lam 33'to ground. Lamp33 which is located adjacent to jack 5at the operators position at'A is'now lighted toiindicate that approximately five minutes have passed. This represents the period of time allowed for conversation, for which the deposited coin constitutes payment.

'Theoperator at A noticing the lighted lamp 33 nowinserts the plug'3i of cord 7"into ack 5 and thereby enables her telephone .set to be connected-through the cord tothe tip and ring conductors of-trunk CT. Relay 10 is operated over an obvious circuit through the sleeveof jack 5 andplug 34 to open the circuit tor lamp 33 and close a circuittor theoperation of the step-by-step switch to move its brushes into the nineteenth position. The circuit tor the stepping magnet in this case will extend 'from battery, through the-winding ofthe'stepping magnet, through the conits twentieth :terminal.

tacts of relay 225 as hereinbetore traced, and the brush of bank 25, eighteenth terminal, upper inner armature and front contactot relay 10 to interrupter 36 through which a ground is made and interruptedat the rate of120 times per minute. With the brushes in the nineteenth position, relay 11 is operated over acircuit from battery, through the wind.- ing of this relay, second upper a'rmatureand front contact of relay 20, brush of bank 27, through the nineteenth terminal of this bank to ground. Relay'll in operating transmits coin collect current to thepcoin equipment magnet 18 over acircuit from the coin collect battery 228, lower outer armature and front contact of relay 223, nineteenth terminal of bank 26, the brush of this bank. through the upper .and lower inner armatures and front contacts of relay 11, and the .tip and ring conductors through the line finder 4 over the calling subscribers line to ground through magnet '18. vMagnet 18 is therebyoperatedin a direction to collect the coin 19in paymenttor the first conversation periodof fivesminutes.

Relay 11 in operating also closes la circuit for the/operation of stepping'magnet 28 from battery,'through the winding of this'magnet, lower'outer armatureandtront contact of re.- lay '11 to ground at interrupter ;36 at the next connectionot groundrtherethrough. The stepping magnetnow steps the brushes to the twentieth position and as the ground at interrupter 36 1s connected once every half second, relay 11 will remain operated tor-onehalf second which is sutiicient to insurethe operation of magnet 18. WVith the brushes in the twentieth position relay 11 will release as the bank 27 is not provided with ground on The operator at A now connects her telephone set to-the cord 7 and is therebytelephonically connected to 'both subscribers but electrically 'onlyto the calling subscriber as relay 10 in operating opens the direct connection over trunk OT'to the called subscriber, the connection now :being extended through condensers 36 and 37. The operator may now inform the calling subscriber that the first five-minute period of conversation has passed and that in case the conversation is to-rbe continued, another coin must :be deposited. WVhen the calling'subscriber deposits the coin the operator at A will observe this in the usual manner but in case she has not observed that the coin was deposited, she may associate her own co-in collect equip It the parties desire to terminate when she removes the plug 3& from jack 5.

"Thestepping' switch is thereby returned to normal from the twentieth position due to the 'factthat relay 20 is-released in a manner hereinafter described. The circuit for the stepping magnet 28 in this case will extend from battery, through the winding of the stepping magnet and its armature and back contact, upper middle armature and back contact of relay 20, brush of bank 27, the twentieth and twenty-first terminals of this bank, make-before-break contacts of relay 20 to ground. The operator remains on the line in order to prevent the step-by-step switch from starting a second cycle of operation on returning-to normal which would be the case if the relay 10 is released before relay 20 as will be explained hereinafter.

If on the other hand it is decided to con tinue the conversation the calling subscriber deposits a second coinfor a second period of five minutes-of conversation. The operator receives the usual indication of this fact and removes the plug 3 1 from jack 6. Relay 10 is then released and the stepping switch returned to normal position by the'closure of a circuit from battery, winding of magnet 28, lower armature and front contact of relay 225, lower inner armature and front contact of'relay 20, brush of bank 25, twentieth and twenty-first positions of this bank, lower inner armature and back contact of relay 10, to ground at interrupter 36. 7 Due to the fact that-relay 20 is maintained operated at this time the 'steppingfswitch will now proceed to go through a second cycle of operation as described to measure off the second conversation period. The circuit closed in the normal position of the brush of. bank25 for the stepping magnet 28 will now move the switch from normal as hereinbeforedescribed when relay 20 was first operated. At the end of the second period of conversationlamp 33 is again lighted and if the conversation is to be continued further the operations described abo-veare repeated until the connection is released.

.Should the calling party refuse to deposit the coin and insist on continuing to talk, the operator will insert the plug of another cord into jack 6. In this case relay 10 is operated over the sleeve circuit-"to separate the two parties telephonically by opening the tipand ring connections through the upper and lower outer armatures and back contacts of relay 40. The operator is now connected through this second cord by the operation 0f these armaturesof relay 40 in order to enable herto talk to either party without being interrupted by the other party. The operator talksto the calling party through cord 7, by operating her listening key in this cord or to the called party through the cord connected to jack 6, jack 6 being connected through condensers 36 and 37 to trunk GT. 7

When the calling party hangs up at the end of the conversation relay 201 is released due to the removal of ground from the sleeve of selector 304 on the release of the selector whether the last conversation period hasexpired or not. If the period has not expired the stepping magnet will be controlled by the circuit completed to ground at the makebefore-break contacts of relay 20 and the interrupter equipment 23 will become inefli'ec tive. If the period has just expired the stepby-step switch will be in position 19 and the u 27 will when relay 20 is released cause the ground on the nineteenth terminal of bank magnet 28 to be operated to step the; switch into position 20 from which it=will be returned to normal as hereinbefore described. Relay 9 is released by relay 20. I I

The release of relay 201; causes the operation of relay 207 over a circuitasfollows'. battery, second upper inner armature and back contact of relay 201, winding of relay 207, lower make-before-break contacts of" this relay, inner lower armature and front contact of relay 202 to ground. Relay 207 in operating opens the original circuit to battery for relay 12. It ,shouldjbe observed however that relay 12 is already released. Relay 207 is looked through its lower armature and front contact under control of relay 202. Relay 8 is operated through tlne oper ation of relay 207 over a circuit as follows: battery, inner upper armature and'back contact of relay 201, upper outer armature and front contact of relay202, upperouterarma ture and'front contact of relay 207, winding of relay 8, lead 231 to interrupter 230 which establishes a connection to groundonce every second. 7 a f o The operationof relay 8 applies coinrcollectbattery 228 through the lower outer arm: ature and front contact of relay 223, winding of, relay 234, upper and lower inner armatures and front contacts of relay 8-th ro'ugh the tip and ring conductorsof trunk CT through the magnet 18 to ground. ,Relay 234: operates in this circuit and provides' a holding circuit for relay 216, which would ordinarily release on the operation of relay o releases and has no opportunity to operate a second time from ground at interrupter'230, unless magnet 18 fails to operateon the first impulse Relay 234in releasing causes the release of relays 216' and 202 in success on and the release'of relay'202 will preventtb reop'e'r'atio'n of relay 8 by the opening of the energizing circuit therefor. Relay 202 in releasing causes the'release of relays 22 i and 225 in succession and relay 225 opens the circuit for the stepping magnet 28. Relays 223 and 207 are also released by relay 202.

If the callingsubscriber at 1 is entitled to free Service, that is, it the call is not to be charged for, the coin magnet 18 is operated to refund the coin; In this case the connector 305 will be of the type in which the battery connection is not reversed Over the line and the relay 222 will therefore not be operated when-the called subscriber answers. Relays 228; 224 and 225 are therefore not operated. Hence relay 20 is not operated to operate re- 9, nor is the circuit for the stepping mag lit28 completed. Consequently relays 208 see 12 willremain operated under control of relay 217 and conversation between the subscriber wi-ll therefore be carried on over the connection through the condensers 16 and 17. It is further evident that no control can be exercisedby the opcrator at A over the collection or refunding of coins under these circumstances; nor is this necessary as all that is required is to return the coin deposited by the calling subscriber to enable him to make the call. To this end; when the connection is released and relay 8 operates coin refund battery 38 will be supplied through the upper cuter armature and front contact of relay 8, ldwer outer armature and b'ack contact of relay 223 to the coin magnet 18 to cause it to operate to refund the coin; The circuit will otherwise be released in the heiieinb'efore described.

In case the connection is to be extended to an operator at AB instead of to a local subscriber the selector 304 will be actuated to connect with the terminals of the trunk AT. When this takes place the trunk loop is connected to" ground and battery through the windings or relay 306 and through upper makebefo-re-break contacts and lower arma tare and back Contact of relay 307. Relay 306 e erates and causes the operation of relays 308 andi309over obvious circuits. Relay same manner as in operating applies a ringingtone from the SOurc'e 310 through the ring conductor oftrunk CT to the calling subscriber to indigate that the connection has been extended to the operator at AB. The trunk light 311 is also lighted over an obvious circuit by the operaati or relay 308 to indicate to the op erator at AB that a connection is desired over trunk AT at jack 302.- The operation of re lays 309 and 308 apply a'busy. ground to the sleeve terminal of trunk AB to cause the trunk CT to function as hereinbet'ore described when the ground is connected on the sleeve of switch 304. The operation of re-' lay 306 also closes an obvious circuit for the operation of relay 312 and this relay in turn closes an obvious circuit for the operation of relay 313. p

The operator at AB will now insert plug 301 into jack 302 and this causes the operation of relay 307 over the sleeve conductor from battery in the operators cord. Relay 307 in operating opens the circuit for relay 306 which in turn causes the release of relay 308. Relay 308 in releasing removes the tone to the calling subscriber and extinguishes the trunk lamp 311. Relay 309 would also release on the release of relay 306 except that it is slow in releasing so that it will be niaintained operated by the operation of relay 307 which closes a circuit to ground at its upper inner armature and front contact to main tain the ground on the sleeve of selector 30 i.

Relay 307 in operating connects the trunk CT to thetrunk AT and also causes the release of relay-s 312 and 313. Relay 31 2 is slow in releasing to permit relay 313 to be held operated long enough after relay 307 is operated to transmit a momen tary impulse of increased current over the trunk CT from battery 316 and ground 317. This momentary increase of current causes the operation of the marginal relay 219 in trunk CT which is at this time bridged across the tip and ring conductors of-trunk CT due to the operation of relays 217 and 12. Relay 219 in operating causes the operation of relay 20. The operation of relay 20 has no effect as far as the starting of the coin collecting and refunding means is concerned. That is, the stepping magnet 28 will not be operated as relay 225 has not been operated since there has been no reversal of current in the trunk AT. This means of con trolling the collection is not needed at this time as the coin collecting during conversa tion will be attended to by the operator at AB in the usual manner. The operation of relay 20, however, closes a circuit for the operation of relay 9 so that circuits will be coinpleted from the calling subscriber to the op"- erator at AB without any electrical obstruction. That is, with relay 10 not operated and relay9 operated a connection is closed through trunk GT, past the condensers 36 and 37 and through tip and ring conductors 30 and 31 directly to the cord of the operator at AB. The operator at AB will now converse with the calling subscriber and extend the connection to the desired wanted subscriber in any well-known manner;

It should be pointed out at this time that with a circuit of the type of trunk CT it is desirable thatthe trunk should be of the re: peater type during the dialing period and of the type in Which no electrical obstructions are present on the trunk when a connection is fully established. This is due to the fact that the coin collecting equipment associated with the subscribersstation causes the operation of the pulsing relay 217 with both conductors the condensers 16 and 17. It has heretofore from the calling subscribers station involved. Hence, the tip and ring conductors to the selector 304 have to be separated from the conductors leading to the calling subscriber by.

been described how the condensers divide the circuit during the dialing and how the connection is fully completed to the calling subscriber and to the called subscriber or to the operator at AB to eliminate all electrical obstructions. Should the connection be extended to a test man or other supervisory operator only a talking connection will, as hereinbefore described in connection with free calls, extend over the trunk C'I arranged as a repeat-er type trunk.

When the conversation is ended the operator at. AB collects the coins deposited in payment for the call by operating her usual equipment provided in connection with the cord circuit for this purpose. The collection is done by applying collect battery to the line and thereby operating the magnet 18 accordingly. If the call is fr'ee the operator applies refund battery to the line to operate the magnet 18 to refund the coin that the calling subscriber deposited to enable him to make the call. Refunding by the operator atAB may, however, be done at'anyother time during conversation, for example in case of dispute. On the other hand when the operator at AB disconnects by removing plug 301 from jack 302 the circuits of trunk CT are operated to apply refund battery to magnet 18 so that in case any coins deposited remain in the coin box they are refunded. Relays 307 and 309 are now released and the circuits of trunk CT will then function in the manner as hereinbefore described on the removal of ground from the sleeve of selector 30 1 tooperate relay 8 to refund the coin. a

It should be understood that while the invention has been described in connection with but one disclosure, it is not limited thereby, and that the invention could be applied to many other circuit arrangements without departing from the spirit thereof.

What is claimed'is: Y

1. In a telephone system, a calling station, a called station, an operators position, a trunk, means including said trunk for connecting the calling station with eitherthe called station or the operators position, coin collecting and refunding means associated with said trunk, and means for rendering said collecting and refunding means effective when a connection is extended to the called station and for maintaining said collecting and refunding means ineflective When the connecti on is extended to the operators positions 2. In a telephone system, a calling station, a coin collecting and refunding device thereat, a trunk, means for extending a connection from the calling station to. said trunk, coin collecting and refunding means associated means in said trunk to collect or refund a com trunk to the called subscribers station and for actuating the coin collecting and refunding depending on whether or notth'e connection to the called subscriber is successful, an operators position, 'andmeans for extending the connection from 'thetrunkto the operators position and for disabling the coin' collecting and refunding means when the connection is so extended. 7 1 Y 3: In a telephone system, acalling station, a called subscribers station, means including a trunlrfor establishingconnections between said stations and means associated with said trunk for controlling the collection and re funding of coins, a cord at-an operators position, a swltching trunk accessible from sald first mentioned trunk and terminating at said operators position, and means for maintaining the'coi-n collecting and refunding control means ineffective and for converting the first mentioned trunk from a repeater type trunk to a direct connection typetrunk free fromany electrical obstruction when. a connection is established between said trunks and between the switching trunk and the COId;'-

4. In a telephone system,a calling station, a called station, an operators position, a 1 trunk, meansincluding said trunk for connecting the calling station'with the called station or the operators position; 'coinicollecting and refunding means associated with s'aidtrunk, and means'for converting the trunk from one type of transmission'circuit to another type'and for maintaining the coin collecting and refunding means ineffective when a connection is established to the operators position andfor rendering said collectmg and refunding effective when a connection i's' extended to the called stationI;

Ina telephone system, a calling station, a called station, an operators position, a trunk, means including said trunk for connecting the calling station with the called station or the operators position, means re sponsive to the connection of the calling station to the operators position for transmitting a momentary impulse of current to the trunk, and means in said trunk responsive to H said impulse for converting the trunk'from one type of transmission circuit to another type.

'a called station, an operators position, a

trunk, automatic switches, means 'in said trunk for repeating impulses to operate said '6. In a telephone system, a calling station, 2

tion for disabling said toll-charging means and for converting said trunk into a direct transmission circuit free from said repeating means a 1 7. In a telephone system, a calling station, a called station, an operators position, a trunk, means including said trunk for connecting the calling station with either the called station or the operators position, coin 10 collecting means associated with said trunk, a polarized relay associated with said trunk, means responsive to the establishing of a connection to a called station for actuating said relay, means responsive to the actuation of said relay for operating said coin collecting means to collect the coin deposited at the calling station, and means vfor maintaining said relay in non-actuated condition when a connection is established to the operators position to prevent the operation of the coin collecting means. i 8. In a telephone system, a calling station, a called station, an operators position, a trunk, means including said trunk for conmeeting; the calling station with either the called station or the operators position, coin collecting means associated with said trunk, a polarized relay associated with said trunk, means responsive to the establishing of a con- '80 motion to the called station for actuating said relay, means responsive to the actuation of said relay for operating said coin collecting means to collect the coin deposited at the calling station, and means for maintaining said relay in non-actuated condition to prevent the operation of the coin collecting means and for converting said trunk from a repeater type trunk to a directconnection type trunk free from any electrical obstruction when a 4,0 connection is established to the operators position. V a

In witness whereof, I hereunto subscribe my name this 29th day of March, 1929.

, RAY L. STOKELY. 

